1. Field of the Invention
The present invention relates to a dosage pump of the type having a piston sealingly engaging with the inner surface of the cylinder and movable between a first position or top position and a second position or bottom position, the volume defined in the cylinder by the piston communicating with inlet and outlet passages. If a one-way valve or check valve is provided in each of said inlet and outlet passages or in conduits communicating therewith, and the inlet passage is connected to a liquid container or another liquid source, movement of the piston between its first and second positions within the cylinder results in discharge of metered or dosed amounts of liquid from the liquid container through the outlet passage of the pump.
2. Description of the Prior Art
It is known to use dosage pumps of this type in connection with for example liquid analyzing apparatuses such as blood or milk analyzing apparatuses, for passing metered or dosed amounts of liquid samples into the apparatus. A liquid analyzer provided with such dosage pump is disclosed in U.S. patent application Ser. No. 894,389.
It has been found that results obtained by analyzing a number of identical liquid samples in such liquid analyzing apparatus provided with a manually operated dosage pump of the above type quite often differ to an unacceptable degree, and this is especially true when the dosage pump is operated by different persons.